Forcing Part Order - Heat Corner Parts First?

I'm going to create a second STL file that comprises of parts slightly offset from the main part with the intention of stopping sharp corners on my part cooling too much and curling free. How do I force the order at which Slic3r processes the parts? Is it simply first part processes first or does it tend to do perimeters then hatch etc?

I'll be experimenting and update this thread if I find my answer before someone else replies!

Corners don't lift because the part cools too much. They lift because they don't cool enough. The nozzle spends a relatively long time in a corner because it is slowing down as it enters the corner, then speeds up again as it leaves. While it's there, it is depositing plastic and heating the previous layers. If you print another object, like a cylinder, maybe a few cm away from your part, the time it takes the extruder to print the other object and travel back and forth will give your print time to cool so that the corners don't lift.

You don't have to do anything fancy. Just add a cylinder to the bed a few cm away from your main print. The sacrificial part should be the same height as your target print.

If you're printing PLA, turn on the print cooling fan, too. If your printer doesn't have a cooling fan, add one. It makes a huge difference in PLA print quality and is well worth the minor expense and effort.

Edited 2 time(s). Last edit at 12/12/2017 07:29AM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Interesting. I will think about it more.

The part I'm building is a large benchmark part. About 100*120mm ABS. It's almost a worse case for part curl (or at least would be in a sintering environment, I'm assuming the same for extrusion) due to the large flat area. Layer to layer time is in the order of minutes so doubt scanning an extra part would make much difference?

I'm slowly stepping up the bed heater set point. Got a bed temperature of 105 at the moment, but it drops off to the edge of the build area. I'll see if the heater can hold another 10C.

This is what I was looking to do:

[hydraraptor.blogspot.de]

Oh, not PLA and not small...

ABS is a completely different animal. Is your printer enclosed, and is it 45-50C inside? If not, you're not likely to be able to print anything with any bulk in ABS without it delaminating. You can print single walled vases and very small parts without a warm enclosure, but bulky parts are out of the question. The bed temperature doesn't really affect anything more than a few mm above the bed surface, except that is also the main source of heat for an enclosure.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Argh. Was hoping to get a bit closer without an enclosure! My first thoughts would be to a closed box sitting over the machine to part way down the sides with a fan to such out air from the he highest point if it gets too toasty. Like yoi say the heated bed should be plenty to get things warming up.

I have used 2 plastic bags over the printer to create a temporary enclosure for printing ABS.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Cheers, that's another option. I was considering a big cardboard box! Think the lab being cold yesterday really wasn't a help. Temp limit for the duets? If I build an enclosure I'll be moving the duet to the outside.

Quote
WesBrooks
Cheers, that's another option. I was considering a big cardboard box! Think the lab being cold yesterday really wasn't a help. Temp limit for the duets? If I build an enclosure I'll be moving the duet to the outside.

The parts used on the Duet are all rated at 85C or higher. You can monitor the MCU temperature in the web interface, but you need to calibrate it first - see [duet3d.com].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I made this a few years ago.

PIR is about as close to fireproof as you'll ever get, and it's pretty cheap. You can hold the whole thing together with duct tape and have it built in about 15 minutes.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks for the information dc42. I had a quick hunt on the duet wiki but missed/couldn't find the bit on temperatures. I will look at setting up the MCU temp sensor though regardless.

Thanks digital_dentist for the suggestion of PIR. I hadn't realised this had flame retardant properties. The metal skin could help with noise suppression too!

The metal skin is just foil, but the bulk of the insulation does reduce noise a bit. The foil should reflect heat a little, too I would think, so I put that side on the inside of the enclosure.

The fireproof aspect of the foam doesn't really do much good if the whole thing is held together with tape or printed plastic bits that will melt or burn, allowing the enclosure to fall apart. But if the printer ever does catch fire, burning foam won't add to the problems.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I was thinking electrical noise but I've had no complaints yet so not really an issue. If practical I'll bond the foil to earth, it won't hurt! I'll be using that foam in some sort of frame work. I'm going to look at an automatic extinguisher, so the chamber needs to hold together when that releases and vents through a weighted flap.